1. Technical Field
The present invention relates to a projector adapted to project an image formed by a light modulation device such as a liquid crystal panel on a screen.
2. Related Art
As a projector of the related art, there exists a projector provided with two discharge lamps, and adapted to combine the light paths thereof while folding the light paths with two reflecting mirrors and a reflecting prism (see JP-A-2000-3612 (Patent Document 1)).
As another projector, there exists a projector provided with two lamp unit sections and adapted to combine the light paths thereof while folding the light paths in two steps with a combination mirror section (see WO2004/034142 (Patent Document 2)). In this projector, the luminance distributions of the two discharge lamps are adjusted by a position adjustment of the combination mirror section. It should be noted that the Patent Document 2 also discloses a projector provided with two lamp unit sections and adapted to combine the light paths thereof while folding the light paths with two mirrors as a still another projector, wherein each of the mirrors is rotated around an axis perpendicular to a plane including the optical axis.
However, since it is required in the projector disclosed in the Patent Document 1 to guide the light beams from the two discharge lamps to each of cells of integrator lens after appropriately aligning the light beams, it is difficult to combine the light beams from the two discharge lamps without omission to use them as the illumination light. For example, in the case in which there exists misalignment in an attachment angle of the mirror disposed in front of the integrator lens or misalignment in attachment positions of the two discharge lamps, the probability of the light source image running off either of the cells of the integrator lens is increased, and there is a possibility that the luminance of the illumination is caused to drop, and that the illumination distribution is disturbed.
Further, in the projector disclosed in the Patent Document 2, although the uniformity can be assured using the combination mirror section and the two mirrors even in the case in which one of the lamp unit sections is only lit, the uniformity is not necessarily assured in the case in which the light beams from the both lamp unit sections are used simultaneously. In other words, in the case in which the combination mirror section is moved, or the two mirrors are rotated, both of the incident position and the incident angle of the illumination light into the integrator lens change simultaneously, and therefore, the precise alignment of the illumination light taking the incident position and the incident angle into consideration is difficult.